1. Field of the Invention
The present invention relates to a film for a first-aid sticking plaster, and more particularly, it relates to a film for a first-aid sticking plaster which can obtain a flexible first-aid sticking plaster having excellent feeling, with a low possibility of compressing the affected part.
2. Description of the Background Art
In general, a sticking plaster, particularly a first-aid sticking plaster is prepared through the following steps: First, a soft film is prepared so that its surface is coated with an adhesive, and a gauze or the like is attached onto the adhesive. Further, a separator is disposed on a gauze to obtain a layered product. Then, the layered product is punched into prescribed dimensions, and packing papers are superposed on front and back surfaces of the punched layered product and cut into prescribed dimensions, to obtain a first-aid sticking plaster.
The soft film employed for the aforementioned first-aid sticking plaster is generally made of a material which is mainly composed of plasticized polyvinyl chloride (hereinafter referred to as plasticized PVC) prepared by calendering or sol casting, in consideration of flexibility, stretchability and feeling.
However, a plasticized PVC film contains a plasticizer in a large amount. Thus, the plasticizer may be transferred from the film toward the adhesive to reduce its adhesion or adhesive strength between the film and the adhesive, leading to separation of the sticking plaster. Further, problems in employment of plasticized PVC, which is a polymer containing chlorine, are recently discussed in all fields in consideration of environment.
To this end, positive development is now being made on polyolefin resin having flexibility and high stretchability, as a material for taking place of the plasticized PVC.
A film of such polyolefin resin is prepared from polyethylene, an ethylene-vinyl acetate copolymer, polybutadiene or an ethylene-propylene copolymer, for example. Japanese Patent Publication No. 57-11342 (1982) discloses a Film for a first-aid sticking plaster which is prepared by drawing a polyolefin composition consisting of at least one of an ethylene-.alpha.-olefin copolymer, LDPE (low density polyethylene) and PP (polypropylene) by 1.5 to 3.5 times, while Japanese Patent Laying-Open No. 62-82967 (1987) discloses a film consisting of a hydrocarbon elastomer such as ethylene-propylene rubber or an ethylene-propylene-diene ternary copolymer and a polyolefin compound such as an ethylene-vinyl acetate copolymer.
However, such a film of polyolefin resin is insufficient in stretchability and stress relaxation in application, which are required for a first-aid sticking plaster. Namely, the film is so insufficient in stretchability that the first-aid sticking plaster may be loosened immediately after application. Further, the film is so insufficient in stress relaxation that the first-aid sticking plaster compresses the affected part upon application or is separated immediately after application. Thus, the film is not necessarily suitable for actual use.